1. Field
The embodiments described herein pertain generally to a multi-level programming method of a phase-change memory device.
2. Discussion
A phase-change memory device (PRAM) among next-generation memory devices has the most excellent property and has been closest to mass production. Further, as compared with other memory devices, the PRAM is relatively simple in structure and manufacturing process and can be applied to both of a stand-alone memory and an embedded memory for SoC, and, thus, it has been regarded as one of ultimate memory devices.
However, in order to commercialize such a phase-change memory device, it is necessary to realize a multi-level cell capable of storing two or more bits of data in a cell as a minimum storage space of a memory for high integration.
The multi-level cell can store multiple bits of data per cell unlike a conventional single-level cell that stores one bit of data per cell, and, thus, it has an effect equivalent to reducing a physical size of the phase-change memory device.
In this regard, Korean Patent Laid-open Publication No. 10-2010-0009325 (entitled “Multi-level phase change random access memory device”) describes a phase-change memory device that includes a phase-change material layer formed of a phase-change material having two different phases (two or more phases) and can store multiple bits of data in a cell.